fenfill developer docs

fenfill finds the fields on a blank PDF form. The fenfill MCP server lets your agent use that, then fills the form on your own machine, so the answers never reach us. Everything here works with a fenfill API key, on Pro and above.

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Where to start

QuickstartGet a key, add the MCP server to your client, and fill your first form.
MCP serverSetup for each client, the 13 tools, settings and troubleshooting.
API referenceEvery /v1 endpoint, with parameters, schemas and curl examples.

Changelog · @fenfill/mcp on npm · Source on GitHub · For agents

How data flows

Your agent calls analyze_form with a blank PDF. The MCP server uploads it to fenfill once. It is encrypted as soon as it arrives.
fenfill finds the fields and returns them: ids, types, labels and positions. The MCP server caches the result on your machine.
Your agent calls fill_form with the answers. The MCP server stamps them into a new PDF on your machine. Nothing is sent.

Unless you save it as a template, the blank PDF is deleted when its analysis finishes, and the analysis is kept for at most 24 hours, or 1 hour after it is first fetched. The full table is on What is sent where.